Cyanide protects Escherichia coli NADH dehydrogenase activity from MccJ25 inhibition

GALVÁN E; CHALÓN MC; SCHURIG-BRICCIO L; MINAHK CJ; GENNIS R; BELLOMIO A

Carlos Paz, Córdoba

Congreso; XLII Reunión Anual de la Sociedad Argentina de Biofísica; 2013

Sociedad Argentina de Biofísica

Microcin J25 (MccJ25) is a 21-residue ribosomally synthesized antibacterial lasso peptide. It is produced by Escherichia coli, and is active against close-related bacteria including certain human pathogens like Salmolella enterica and Shigella spp. MccJ25 mode acts in susceptible bacteria inhibiting the RNA polymerase and the bacterial membrane respiratory chain. The rate of cell oxygen consumption is lower in the presence of the peptide. In a previous report was shown that MccJ25 was able to inhibit in vitro the NADH dehydrogenase activity by 20% approximately [1]. In the present work we observed that when 6 mM cyanide is added to the reaction the inhibition decreased to 10%. E. coli has two respiratory oxygen reductases (terminal oxidases), cytochrome bd and cytochrome bo3, both of these enzymes are quinol oxidases. Cyanide inhibits both enzymes. The antimicrobial activity and the effect of MccJ25 on NADH dehydrogenase activity of E. coli membrane belonging to wild type and terminal oxidases mutants were assayed.